The present invention relates generally to crankcase ventilation systems for internal combustion engines and, more particularly, to oil drain tubes for returning condensed engine oil from an oil separator of a crankcase ventilation system to an oil sump.
Oil breather elements or oil separators have been used in internal combustion engines in order to condense and recover oil vapor circulating through crankcase ventilation systems. While it is desirable for the oil to be returned to the engine oil sump, such return of oil can also be affected by foaming due to interaction with xe2x80x9cblowbyxe2x80x9d gases and exposure to undesirable contaminants entrained in blowby gases.
U.S. Pat. No. 5,852,992, issued to Boggs et al. on Dec. 29, 1998, discloses an internal combustion engine having a crankcase ventilation system that includes separate oil drain-back and crankcase ventilation passages. In order to prevent blowby gases from flowing past draining oil, the oil drain back passages are configured to extend from the cylinder head to a position below the top level of oil in the crankcase of the engine.
Such a configuration may not be feasible in some engine applications. For example, in some engines, the top level of oil in the engine is below the engine block (e.g., where the nominal oil level has a top level below the top of the oil pan), and some engine blocks have crankcase ventilation passages that extend only down to a position above the top level of oil in the engine crankcase.
The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.
In accordance with one aspect of the present invention, an oil drain tube for an internal combustion engine is provided. The oil drain tube comprises a first non-horizontal tube portion in direct fluid communication with an oil separator, a second non-horizontal tube portion in direct fluid communication with an oil sump and a third tube portion connecting the first non-horizontal tube portion and the second non-horizontal tube portion in fluid communication with one another.
In accordance with another aspect of the present invention, a positive crankcase ventilation system is provided for an internal combustion engine having an engine block and an oil separator. The positive crankcase ventilation system includes an oil drain passage in the engine block wherein the drain passage is disposed in fluid communication with the oil separator, and an oil drain tube. The oil drain tube has a first non-horizontal tube portion in direct fluid communication with the oil separator, a second non-horizontal tube portion in direct fluid communication with an oil sump and a third tube portion connecting the first non-horizontal tube portion and the second non-horizontal tube portion in fluid communication with one another.
In accordance with a still further aspect of the present invention, an internal combustion engine includes an oil sump, an oil separator, an oil drain passage in fluid communication with the oil separator and an oil drain tube. The oil drain tube has a first non-horizontal tube portion in direct fluid communication with the oil separator, a second non-horizontal tube portion in direct fluid communication with the oil sump and a third tube portion connecting the first non-horizontal tube portion and the second non-horizontal tube portion in fluid communication with one another.
Other aspects and features of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims.